Well than it will couple into other parts of the circuit. But still it can couple a disturbance into the circuit. Please note that this must not be a mobile phone. That is just an illustration of a coupled disturbance signal that can come from any EMI source.
The picture is for illustrative purpose only! A mobile phone is depicted since it is assumed, that radiated noise is coupled to line and return with respect to GND.
Ok, but my assumption is that maybe the possition and the distance beteween mobile phone and "DUT - device under test" has also infuence/impact. Is this correct? If yes, how is it considered?
Hi OMICRON Lab, is that why on SMPS of TVs the use a capacitor between the HOT GROUND (AC) and the COLD GROUND (DC). See image from google below: electronics.stackexchange.com/questions/268597/coupling-between-hot-ground-and-cold-ground
Yes this is correct. The hot side needs to be isolated from the DC side for safety reasons (you can see that they have different ground symbols). But if we completely isolate, there is no low impedance path for the common mode currents to return to via the cables. If they cannot return, they have nowhere to go and therefore will radiate into the air and this could cause a failure in the radiated emissions test. We cannot connect the two grounds with just a wire as we will then lose isolation. So the same high-frequency Y caps between the Hot and DC grounds will allow common mode currents to return via the cables whilst maintaining the isolation.
Excellent video. Thank you.
How about the scenario when the mobile phone is placed on top of the buck converter and not in between cables?
Well than it will couple into other parts of the circuit. But still it can couple a disturbance into the circuit. Please note that this must not be a mobile phone. That is just an illustration of a coupled disturbance signal that can come from any EMI source.
The picture is for illustrative purpose only! A mobile phone is depicted since it is assumed, that radiated noise is coupled to line and return with respect to GND.
Ok, but my assumption is that maybe the possition and the distance beteween mobile phone and "DUT - device under test" has also infuence/impact.
Is this correct? If yes, how is it considered?
Of course it will have an impact on the size of the disturbance. But that was not considered or calculated in this case.
thank you sir, neat and clear
You are welcome!
very good explnation! Thanks!!!
Thanks!
Holly fuck that pen is HORRENDOUS!
We are sorry for that!
Hi OMICRON Lab, is that why on SMPS of TVs the use a capacitor between the HOT GROUND (AC) and the COLD GROUND (DC). See image from google below: electronics.stackexchange.com/questions/268597/coupling-between-hot-ground-and-cold-ground
Yes this is correct.
The hot side needs to be isolated from the DC side for safety reasons (you can see that they have different ground symbols).
But if we completely isolate, there is no low impedance path for the common mode currents to return to via the cables. If they cannot return, they have nowhere to go and therefore will radiate into the air and this could cause a failure in the radiated emissions test.
We cannot connect the two grounds with just a wire as we will then lose isolation. So the same high-frequency Y caps between the Hot and DC grounds will allow common mode currents to return via the cables whilst maintaining the isolation.
@@OMICRONLabTutorials Noted. Thanks for the answers! I am looking forward to watch Part 2 to 7!